Aliaa Magda Elmahdy apparently thought she was striking a blow for sexual equality and free expression in Egypt when she posted nude photographs of herself on a blog. Instead Ms. Elmahdy set off a wave of outrage inEgypt, stoking conservative Islamist sentiments that many liberals fear will undermine their prospects in the country’s parliamentary election in November.

It is hard to overstate the shock at an Egyptian woman’s posting nude photographs of herself on the Internet in a conservative religious country where a vast majority of Muslim women are veiled and even men seldom bare their knees in public.

InEgypt, even kissing in public is taboo.

It is often the case that activists willing to defy social conventions, pushing the boundaries of what is considered acceptable anywhere, succeed in provoking discussion — while finding themselves ostracized and isolated.

Indeed, Ms. Elmahdy learned that reality quickly after a Twitter post directed attention to her blog, and her pictures.

Soon Ms. Elmahdy, a 20-year-old activist, found herself swept up in a campaign season political fight, especially among liberals battling conservative Islamists in the first election since President Hosni Mubarak was ousted from power.

But if she thought she would get support from the left, she was wrong.

“Many movements inEgypt, particularly Islamist movements, are trying to benefit,” said a parliamentary candidate from the left-leaning Egyptian Social Democratic Party. “They say, ‘We have to protect our society from things like this, and if the liberals win then this woman will become a model for all Egyptian women.’ ”

Liberal activists raced to disavow any connection to her. After reports this week indicated that Ms. Elmahdy was a member of the April 6th Youth Movement — a major player in the January revolt that unseated Mr. Mubarak — its spokesman told the pan-Arab news channel Al Arabiya that “the movement does not have any members who engage in such behavior.”

“We are conservative youths, and we always encourage our members to be role models as far as ethics are concerned,” even barring atheists, Mr. Kholi said. “How can we have accepted the membership of a girl who behaves like this?” (Ms. Elmahdy confirmed in a Twitter posting that she did not belong to the group.)

Ms. Elmahdy — whose boyfriend, Kareem Amer, spent four years in jail for writings deemed insulting to Islam and Mr. Mubarak — posted the photographs with a statement declaring them an act of rebellion against Egypt’s conservative culture and “sexual complexes,” in the spirit of the revolution.

“Try nude models who worked in Fine Art Faculties in the early 1970s, hide all art books and smash naked archaeological statues,” read the statement, alluding to some recent protests staged here by ultra-conservative Islamists known as Salafis. “Then take off your clothes and look at yourselves in the mirror, then burn your body that you so despise to get rid of your sexual complexes forever, before subjecting me to your bigoted insults or denying my freedom of expression.”

Soon after the post went live, apparently admiring allies sent out Twitter messages in support, inaugurating the nationwide debate. “A feminist #Jan25 revolutionary posted her nude photo on the internet to express her freedom. I’m totally taken back by her bravery!!” one ally, Ahmad Awadalla, a human rights activist, said on Twitter.

Ms. Elmahdy did not respond to a Twitter request for comment, and her phone number was unavailable.

The uproar over her pictures echoes a debate that flared up in Tunisia in October on the eve of its first free election, when a television station broadcast a film that is critical of the Islamist takeover after the Iranian revolution. Although some liberals said they had hoped that the animated film, “Persepolis,” would warn Tunisians about the dangers of an Islamist victory in their country, one scene violated an Islamic prohibition against personalized depictions of God. The resulting outrage stirred protests across the country, and Islamists cited it as an example of the need to defend their faith as they rode to triumph at the polls.

But inTunisia, it was not clear that many people had actually seen “Persepolis.”

In Egypt, on the other hand, since it appeared, the post with the naked pictures has been viewed more than 1.6 million times and has attracted more than 2,000 comments, though many are quite critical. “Freedom,” wrote one detractor, “is not the same as degradation and prostitution.”